16 STUDIES IN BIRD-MIGRATION 



supposed, directly from cold. They must migrate or 

 starve, and ages of experience have taught them that 

 they must quit their summer homes after their broods 

 are reared, and wing their way to more genial winter 

 quarters, mainly in the south, where food abounds. 



. . . birds that migrate from a freezing shore, 



In search of milder climes come skimming o'er: 



Instinctive tribes ! their failing food they dread. 



And beg, with timely change, their future bread. — Crabbe. 



It must not be supposed, however, that the inigrants 

 of to-day wait until their food supplies fail ; such is not 

 the case, for the migratory habit has become part and 

 parcel of their lives, through countless ages of practice, 

 and they usually depart from the northern lands as soon 

 as their offspring are able to take care of themselves. 

 The Swifts leave our islands, and also southern Europe, 

 some weeks before any failure of their food takes place- — 

 indeed at a period when it is specially abundant. 

 There are imperative reasons, then, why these birds 

 should migrate to winter quarters more or less distant 

 from their summer homes. But what induces them to 

 quit these genial retreats and return northwards in 

 spring ? There are several excellent reasons. Fore- 

 most among these is the well-known passionate attach- 

 ment shown by birds for their native land — their true 

 home — in which the most fascinating period of their 

 lives is spent. This in itself affords the stimulus to 

 seek, at the appointed time, the hallowed scenes where 

 the all-engrossing domestic duties of the year await 

 them, and have for ages been performed. 



Why homeward turned thy joyful wing ? 



In a far ofif land I heard the voice of Spring ; 



I found myself that moment on the way ; 



My wings, my wings, they had not power to stay. — MONTGOMERY. 



